Many produced water flash vessels need to be upgraded or replaced while they’re still in service. Operators often have to deal with increased flow rates or equipment that no longer brings the oil in water levels down to the level dictated by environmental regulations. (The OSPAR conventions dictate that produced water must have an oil in water level below 30ppm before it can be discharged into the sea).

In this instance, Bluewater were relying on a vessel that had already been retrofitted once before, but needed another upgrade to cope with the requirements of the current job. It was outputting water with an unacceptably high oil content and needed a full refurbishment to facilitate the effective treatment of the large volumes of produced water generated by the Haewene Brim.

This presented several challenges: First, we were working to severe space constraints and needed to design a vessel and internals that would fit in a pre-defined space and link up with the rest of the FSPOs infrastructure.

Secondly, we’d need to improve the performance and tolerances of the pressure vessel in question – employing novel technologies to ensure that it could bring oil in water levels down to the client’s desired specification (less than 25 ppm in this instance) and continue performing at that level for the duration of its rated lifespan.

The inside of a flash vessel is constantly exposed to corrosive substances and fast-flowing produced water that can quickly corrode the vessel lining. We’d have to account for this in our design and ensure that the upgraded vessel could cope with these stressors.

After spending a long time studying historic drawings of the old vessel, we set about designing a new vessel and internals that would fit the pre-existing footprint. We made sure that everything would line up inside, and then we set about exploring options to line the flash vessel with a material that would resist the corrosive environment inside the vessel.

After some deliberation, we decided to add an enhanced glass flake lining to resist corrosion and ensure the vessel's longevity.  

And once our plans were approved by the client, we set to work building the vessel in our factory; finishing construction in good time and readying it for transport to the Haewene Brim.

Our client now has a pressure vessel capable of treating produced water in line with their requirements; bringing oil in water levels down below 25ppm at the flow rates required for the FSPO to continue its work unimpeded. The vessel in question will last for decades to come, and should be relatively maintenance free thanks to the installation of an enhanced glass flake lining.